Hospitals, nursing homes, and other patient care facilities typically include patient monitoring devices at one or more bedsides in the facility. Patient monitoring devices generally include sensors, processing equipment, and displays for obtaining and analyzing a medical patient's physiological parameters such as blood oxygen saturation level, respiratory rate, and the like. Clinicians, including doctors, nurses, and other medical personnel, use the physiological parameters obtained from patient monitors to diagnose illnesses and to prescribe treatments. Clinicians also use the physiological parameters to monitor patients during various clinical situations to determine whether to increase the level of medical care given to patients.
For example, the patient monitoring devices can be used to monitor a pulse oximeter. Pulse oximetry is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of a person's oxygen supply. A typical pulse oximetry system utilizes an optical sensor clipped onto a fingertip to measure the relative volume of oxygenated hemoglobin in pulsatile arterial blood flowing within the fingertip. Oxygen saturation (SpO2), pulse rate, a plethysmograph waveform, perfusion index (PI), pleth variability index (PVI), methemoglobin (MetHb), carboxyhemoglobin (CoHb), total hemoglobin (tHb), glucose, and/or otherwise can be displayed on a monitor accordingly.
The patient monitoring devices can also communicate with an acoustic sensor comprising an acoustic transducer, such as a piezoelectric element. The acoustic sensor can detect respiratory and other biological sounds of a patient and provide signals reflecting these sounds to a patient monitor. An example of such an acoustic sensor, which can implement any of the acoustic sensing functions described herein, is described in U.S. application Ser. No. 12/643,939, filed Dec. 21, 2009, titled “Acoustic Sensor Assembly,” and in U.S. Application No. 61/313,645, filed Mar. 12, 2010, titled “Acoustic Respiratory Monitoring Sensor Having Multiple Sensing Elements,” the disclosures of which are hereby incorporated by reference in their entirety.
Blood pressure is another example of a physiological parameter that can be monitored. Many devices allow blood pressure to be measured by sphygmomanometer systems that utilize an inflatable cuff applied to a person's arm. The cuff is inflated to a pressure level high enough to occlude a major artery. When air is slowly released from the cuff, blood pressure can be estimated by detecting “Korotkoff” sounds using a stethoscope or other detection means placed over the artery. Other Examples of physiological parameters that can be measured include respiration rate, blood analyte measurements, such as oxygen saturation, and ECG.